Conventionally, the following Patent Document 1 has proposed a tread pattern for heavy-duty tires used for trucks and buses, the tread pattern being provided with a plurality of circumferentially and continuously extending main grooves and a plurality of lateral grooves each extending between the main grooves as well as between one of the main grooves and a tread edge to form a plurality of tread blocks, for example.
The heavy-duty tires are required excellent wear resistance and uneven wear resistance, in view of economics and saving maintenance. In general, in order to improve the wear resistance and uneven wear resistance, it may be effective to increase the rigidity of the tread portion while ensuring a sufficient rubber volume of the tread portion by decreasing the groove volume of the tread portion.